1. Technical Field
Systems and methods are disclosed for lubricating a transport system, in particular an escalator or a moving walk. The disclosed systems are driven kinematically by a rotating shaft of the transport system and converting the relatively fast rotational motion of the shaft to a slow linear motion for delivering lubricant over prolonged dispense cycles. As a result, the disclosed systems and methods use substantially less lubricant than conventional systems.
2. Description of the Related Art
An escalator includes a plurality of steps that are connected together by one or more circulating step chains forming an endless loop. The escalator steps are arranged to be able to be vertically offset relative to each other along certain portions of the endless loop to create a vertical rise. In contrast, a moving walk includes a plurality of pallets that are joined together by one or more circulating pallet chains for the horizontal transportation. In both transport systems, handrails can be provided that are driven via handrail chains. Step chains, pallet chains and handrail chains are typically coupled to one or more drive units by sheaves or sprockets driven by an electric motor.
To reduce friction and power requirements and to increase the service life of the transport system, the step, pallet and handrail chains should be lubricated at regular intervals. Additionally, escalator and moving walk systems also include parts that require regular lubrication such as bearings, other chains, ropes, etc. Preferably, the lubrication is performed automatically.
Currently available automatic lubrication systems include: “drip-feed” systems or gravity fed systems that supply lubricant intermittently in the form of droplets applied directly to parts needing lubrication; “oil-mist” or injection spray systems that spray or inject lubricant on parts needing lubrication; and continuous feed systems that deliver lubricant in the form of a stream to parts needing lubrication. Each of these lubricating systems have inherent disadvantages.
One common disadvantage is inefficient use of lubricant or wasted lubricant. Because most lubricants are derived from non-renewable petroleum sources, wasted lubricant is becoming a greater concern as companies are being encouraged to reduce their use of fossil fuels, reduce their carbon footprint and conduct themselves in environmentally sensitive ways. Further, wasted lubricant must also be safely disposed of, which may be problematic for the maintenance crew of the transport system or the building owner if a recycling facility is not readily accessible.
Returning to the disadvantages of currently available lubricating systems, drip-feed systems suffer from difficulties in terms of timing the droplet discharge from the nozzle with the link points of each chain link joint. The flow of lubricant typically cannot be easily moderated with drip-feed systems, which means that lubrication also takes place when the escalator or moving walk is stationary thereby resulting in waste. Drip-feed systems also cannot respond adequately to environmental conditions that require different quantities of lubricant. Furthermore, different lubrication requirements of different lubrication points cannot normally be accommodated with drip-feed systems.
Oil-mist or injection-spray type systems disperse lubricant on areas that do not need lubricant, thereby contaminating the surroundings and wasting lubricant. The continuous oil feed systems discharge lubricant at too high of a rate thereby also contaminating the surroundings and wasting lubricant in a manner similar to “oil-mist” lubrication systems. As a counter-measure to the excessive lubrication, an oil pan can be disposed below the power transmission train. However, oil pans must be drained thereby requiring additional labor and maintenance expenses and oil pans obviously do not solve the lubricant waste problem. While operators can be employed to lubricate transportation chains manually, such procedures are costly and expose the operators to unnecessary dangers.
Therefore, a need exists for improved lubricant delivery systems for transport systems such as escalators and moving walks which can more efficiently deliver needed quantities of lubricant than currently available systems.
In satisfaction of the aforenoted needs, lubrication systems for transport systems are disclosed that are powered by a rotating shaft of the transport system. The lubrication system comprises at least one circular member mounted on the rotating shaft. The at least one circular member is coupled to and imparts rotation to a third circular member and separately to a fourth circular member for imparting rotation thereto. The third circular member is coupled to a first linkage. The first linkage extends from the third circular member to a fifth circular member. The fourth circular member is coupled to a second linkage. The second linkage couples the fourth circular member to the first linkage between the third and fifth circular members. The fifth circular member is coupled to a pump shaft. As a result, rotation of the third and fourth circular members imparts rotational movement to the fifth circular member and axial movement of the fifth circular member and pump shaft for pumping lubricant.
A method for pumping lubricant slowly using a rotating shaft of a transport system is also disclosed. The method comprises: coaxially mounting a first circular member and a second circular member on the rotating shaft for rotation with the rotating shaft; providing coaxial third, fourth and fifth circular members and a pump shaft coaxially coupled to the fifth circular member; coupling the first circular member to a third circular member and the second circular member the fourth circular member for imparting rotation to the third and fourth circular members respectively; coupling the third circular member to a fifth circular member with a first rigid linkage; coupling the fourth circular member to the first rigid linkage with a second rigid linkage at a joint disposed between the third and fifth circular members; rotating the first and second circular members with the rotating shaft thereby rotating the third and fourth circular members thereby rotating the fifth circular member and moving the fifth circular member and pump shaft axially, thereby pumping lubricant with the pump shaft.
By varying the difference in combined diameters of the first and third circular members and the second and fourth circular members, the time period for the pump shaft to complete one cycle can be shortened or lengthened.
Other advantages and features will be apparent from the following detailed description when read in conjunction with the attached drawings.
For a more complete understanding of the disclosed methods and apparatuses, reference should be made to the embodiments illustrated in greater detail in the accompanying drawings, wherein:
It should be understood that the drawings are not necessarily to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.
Turning to
The first and second circular members 11, 12 are coupled to second and third circular members 14, 15 respectively. In the embodiment illustrated in
Still referring to
In the system 10 illustrated in
The fifth circular member 23 is coupled to a pump shaft 34 that may be in the form of a bearing housing or cylinder as shown in
Referring to the common axis 36, the joint 26 is spaced apart from the axis 36 by the radius (r). The joint 22 is spaced apart from the common axis 36 by the radius R14.
In the position shown in
In addition to the radial distance R between the joint 22 and common axis 36 and the radial distance (r) between the joint 26 and the common axis 36, other relevant dimensions illustrated in
The first and second circular members 11, 12 are coaxial as noted above and rotate with the same relatively high angular speed, but do not necessarily have the same diameter. The third and fourth circular members 14, 15, rotate at slightly different angular speeds due to their different radii R14, R15 respectively. If the first and second circular members 11, 12 have different sizes, then the third and fourth circular members 14, 15 can be of the same size. The third and fourth circular members 14, 15 are also not necessarily coaxial. Each of the circular members 14, 15 is coupled to one of the linkages 21, 25 respectively. The plane in which the linkages 21, 25 are disposed can be either parallel to the plane of the circular members 14, 15 or inclined with respect to the plane of the circular members 14, 15. In
Due to the spacing of the linkage joints 22, 26, 27, the output joint 24 moves circular with the same diameter of the ring 33 and reiteratively and parallel to the common axis 36. The output joint 24 is connected to the fifth circular member 23 which follows the circular and axial movement of the output joint 24. The bush bearing housing or pump shaft 34 is mounted on the axis 36 and moves axially with the fifth circular member 23. A piston 35 can be mounted in the shaft 34 or vice versa. The iteration period or stroke period time is dependent on the absolute value of the angular velocity difference |ω14−ω15 | between member 14 and member 15 due to the fact that the angular velocities ω14=ω22 and ω15=ω26 are always the same the absolute angular velocity difference can be also expressed by |ω22−ω26|. This difference is dependant on ratio i11=R11/R14 (the ratio between first member 11 and third member 14) and ratio i12=R12/R15 (the ratio between second member 12 and fourth member 15) and the according input angular velocities ω11 of member 11 and ω12 of member 12. The smaller the absolute value of the angular velocity difference |ω22−ω26| the longer the stroke period t. t is infinite when the difference |ω22−ω26| is zero. The ratio R/r (or better the difference R−r) has an influence on the stroke distance s in conjunction with the linkage dimensions a, b, c but, in the disclosed example, only a as seen in equation 3.14. Ratios of the radii R11, R12 of the small circular members 11, 12 and the radii R14, R15 of the larger circular members 14, 15 can vary greatly as will be apparent to those skilled in the art.
Referring to
φ(t)=|0t∫ω22−ω26dt| (0.1)
The variable distance d (t) between the joints 22, 26 can be represented by
d(t)=r(sin(φ(t))/sin(δ(t))) (0.2)
The following kinematical equations and assumptions from the geometry in the top view plane (
d=((R+r cos(φ))2+(r sin(φ))2) 1/2 (1.1)
d=(R2+2Rr cos(φ)+r2)½ (1.1.1.)
The following general kinematical equations and assumptions from the geometry in the XY plane (
a sin(α)=b sin(β) (2.1)
cos(β)=(1−(a/b sin(α))2)½ (2.1.1)
d=a cos(α)+b cos(β) (2.2)
d−a cos(α)=b (1−(a/b sin(α))2)½ (2.2.1)
d
2−2ad cos(α)+a2(cos(α))2=b2−a2(sin(α))2=b2−a2+a2(cos(α))2 (2.2.2)
d
2+[−2a cos(α)]d+[a2−b2]=0 (2.2.3)
p=[−2a cos(α)] (2.2.3.1)
q=[a
2
−b
2] (2.2.3.2)
d
1,2
=−p/2±((p/2)2−q)½ (2.2.3.3)
The distance d is dependent of a (
d=a cos(α)±(a2(cos(α))2+b2−a2)½ (2.2.3.4)
The velocity of the fifth circular member 23 may be calculated as follows. Assuming that a=b, Equation 2.2.14 can be rewritten as:
d=a cos(α)±a cos(α) (3.2)
With the only non trivial solution being d=2a cos(α). Rewriting equation 1.1.1 for d in dependency of φ provides the following expression:
d=2a cos(α)=(R2+2Rr cos(φ)+r2)½ (3.4)
cos(α)=(R2+2Rr cos(φ)+r2)½/2a (3.4.1)
The Y-position of the fifth circular member 23 can then be expressed as:
y(α)(24)=(a+c) sin(α) (3.5)
y(α)(24)=(a+c)(1−(cos(α))2)½ (3.5.1)
The X-position of the fifth circular member can then be expressed as:
x(α)(24)=(a+c) cos(α) (3.6)
x(α)(24)=(a+c) (R2+2Rr cos(φ)+r2)½/2a (3.6.1)
Assuming c=a, the Y-position of the fifth circular member 23 can be written as:
y(φ)(24)=(4a2−R2−2Rr cos(φ)−r2)½ (3.8)
Equation (3.8) can be differentiated for the following Y-velocity equation:
y′(φ)(24)=R sin(φ) (4a2−R2−2Rr cos(φ)−r2)−½ (3.9)
The maximum/minimum Y-position of the fifth circular member 23 can be found by
y′(φ)(24)=0=R sin(φ) (3.10)
with two solutions for φ1,2=0; π. The top Y-position can be expressed as follows:
φtop=π
y(φ)(24)top=(4a2−R2+2Rr−r2)½=(4a2−(R−r)2) 1/2 (3.12)
For the bottom Y-position, φbottom=0 and,
y(φ)(24)bottom=(4a2−R2+2Rr−r2)½=(4a2−(R+r)2)½ (3.13)
With equation (3.12) and (3.13) the stroke distance s (
s=(4a2−(R−r)2)½−(4a2−(R+r)2)½ (3.14)
Equation (3.12) provides the geometrical boundary condition for the minimum dimension for linkage distance a:
a≧(R+r)/2 (3.15)
The calculation of the stroke period is as follows. Using equation (0.1)
φ(t)=|0t∫ω22−ω26dt| (0.1)
For one stroke (φ=2π), a certain time period is required. With
ω22,ω26=const (dω/dt=0) (4.1)
Equation (0.1) can be rewritten as
π=t|ω22−ω26| (4.2)
The angular velocity where R14 (Equations 03, 09) is the radius of the driven circular member 14 (and the joint 22 is disposed on the outer periphery of the member 14 with the radius R. R15 is the radius of the driven circular member 15 and the joint 26 is disposed with the radius r. v22, v26 the corresponding circumferential velocities of the joints 22, 26 can be expressed as:
ω22=v22/R (4.3)
ω26=v26/r (4.4)
Using v0 as the circumferential velocity of the first and second circular members 11, 12 and ω0 the corresponding angular velocity of the first and second circular members 11, 12, and R0 as the radius of the first and second circular members 11, 12. The angular velocities of the joints 22, 26 disposed on the third and fourth circular members 14, 15 can be expressed as:
ω22=ω0R0/R14 (4.6)
ω26=ω0R0/R15 (4.7)
With corresponding ratios expressed as:
R
0
/R
14
=i
22 (4.8)
R
0
/R
15
=i
26 (4.9)
ω22, ω26 can be rewritten as:
ω22ω0i22 (4.10)
ω26=ω026 (4.11)
Equation (4.2) can then be rewritten as:
ω0(i26−i22)t=2π (4.12)
with
ω0=n0π/30[n0 is in Rpm] (4.13)
Δi=(i22−i26) (4.14)
The stroke period can be expressed as
t=60/n0Δi [t in second] (4.15)
The radius dimensions dependent on the required stroke period (t) can be expressed as:
R
0
/R
14
−R
0
/R
15
=Δi=60/(n0t) (5.1)
R
0((R14−R15)/R14R15)=Δi (5.2)
R
14i −R
15
=ΔR (5.3)
ΔR=Δi R
14
R
15
/R
0
=R
14
Δi/i
26
=R
1460/(i26n0t) (5.4)
With R15=R14−ΔR, a relation between the radii and the stroke period can be expressed as:
R
15
=R
14(1−60/(i26n0t)) (5.6)
An example is illustrated graphically in
Finally,
While only certain embodiments have been set forth, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2009/068813 | 12/18/2009 | WO | 00 | 6/5/2012 |